Water Supply Needs Assessment

The existing users have to cover the water supply needs to meet the 20 percent cut back of today. By the time the District reaches build out in 2045, the amount of water represented by a 20 percent cut back will be twice as big – it’s projected that Western will grow by about twice our current size. The new users need to pay for this water supply.

For current water supply conditions, Western’s Riverside Retail area used 20,820 acre-feet last year. For planning purposes, Western assume a MWD cut back of 20 percent of your current use. This would leave Western’s Riverside Retail area with 16,656 acre-feet as water supply for the next year. To make up this short fall, Western must have local supplies. Fortunately, the District has started to develop local supplies in the Chino Basin and a means to deliver this supply via the La Sierra Pipeline Project. This combined with the recycled water used to offset demands on potable water will just about make up the shortage of MWD water.

Clearly, the existing users benefit from these water supply projects, so they are paying for them via the reliability charge.

When Western looks at the ultimate build-out condition, we see that the 20 percent cut is much deeper because the water use has significantly increased due to growth. Even with an increase in the use of recycled water combined with the CDA water, there would be insufficient supply to make up for the MWD 20 percent cut during a drought. To address this, Western will need new water supply to allow for growth.

Western is evaluating various approaches to fund the need for this additional water supply.